Abstract In the solid state, some 3-substituted 4-hydroxycoumarins β-ketoester enols form infinite translational hydrogen-bonded β-chains with varying degrees of alignment between adjacent delocalized systems. Nine related structures have been studied. At the strongest, intermolecular associations are polar, purely translation neighbors interact essentially along a 717 pm crystallographic repeat with shortened 260 pm intermolecular O·O H-bond contacts. Four distinctive features characterize these structures: (1) moderately delocalized β-ketoester enol structures, (2) translational misalignment angles between oxygen donors and acceptors less than 10°, (3) buttressing intermolecular C–H·O contacts co-planar with and near the intermolecular O–H·O interactions, and (4) fully extended ketoester enol hydrogen-bond (ap- anti - anti ) geometries. For non-polar β-chains in related coumarin systems, β-ketoester enol alignments are typically poorer, involve hydrogen-bonding between glide relatives, ap- syn -( anti) geometry, and the intermolecular O·O H-bond contacts are longer. Graphic Abstract Substituted 4-hydroxycoumarins related to phenprocoumon can form well-aligned polar translational β-chains between enolones showing resonance assisted Hydrogen-bonding and a 717 pm repeat along a crystallographic axis.

中文翻译：

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4-羟基香豆素中的β-链氢键

摘要 在固态下，一些 3-取代的 4-羟基香豆素 β-酮酯烯醇形成无限的平移氢键 β-链，相邻离域系统之间具有不同程度的排列。已经研究了九个相关结构。在最强的情况下，分子间关联是极性的，纯粹的平移邻居基本上沿着 717 pm 晶体重复与缩短的 260 pm 分子间 O·O H 键接触相互作用。这些结构有四个独特的特征：(1) 适度离域的 β-酮酯烯醇结构，(2) 氧供体和受体之间的平移错位角小于 10°，(3) 支撑分子间 C-H·O 接触与共面和接近分子间 O-H·O 相互作用，以及 (4) 完全扩展的酮酯烯醇氢键 (ap-anti-anti) 几何结构。对于相关香豆素系统中的非极性 β-链，β-酮酯烯醇排列通常较差，涉及滑行亲属之间的氢键、ap-syn -（反）几何结构，分子间 O·O H 键接触更长. 图形摘要 与苯丙香豆素相关的取代 4-羟基香豆素可以在烯醇酮之间形成排列良好的极性平移 β 链，显示共振辅助氢键和沿晶轴的 717 pm 重复。